The present invention refers to a device for the coupling of excavator teeth which is applicable to the buckets of excavating machines and, in general, to the active working edges of earth-moving machines of similar types.
Machines for civil engineering work which effect the removal of materials such as earth, rocks, etc., generally have active edges on the so-called buckets of the excavators, which are open receptacles of specific shape fixed to the supporting and travelling gear of the machine and which have the function of removing the mass of earth or earth and more or less loose stones, by means of their front edge, collecting in the bucket the materials which have been loosened, allowing them to be transferred to a vehicle for their transport to another site or simply for depositing the mass of earth and stones which has been removed, for its subsequent replacement, for example, in the case of the opening of a trench.
The buckets of excavators and the like suffer significant problems at the active edge because of the high degree of wear to which it is subjected by contact with the earth and stones, which have very abrasive characteristics. For this reason, it is necessary to equip the active edge of the excavator or similar machine with detachable teeth, which are removable components which bear the greater part of the wear by being in direct contact with the mass of earth and stones, and which are therefore parts which wear out very quickly. Said teeth, which are parts that can be exchanged fairly frequently, must combine characteristics which are to a certain extent contradictory, owing to the fact that, being parts which are changed frequently on excavating machines and the like, their price should be relatively low, so it is necessary to exclude mechanization of the teeth, which should be manufactured simply by casting or forging high strength steel. The other contradictory characteristic lies in the need for the mounting of the tooth on the tooth-carrier located at the active edge of the bucket for excavators or the like to be effected with sufficient adjustment to avoid as far as possible any play between the facing regions of the tooth-carrier and the tooth, since the occurrence, otherwise inevitable, of play in the said region results in an increase in the stresses at specific points of contact between the tooth and the tooth-carrier, which further increase the wear locally, in a process which may end in breakage of the parts and which involves changing the worn part, that is to say, the tooth, more or less frequently, according to how the above-mentioned wear phenomena can be controlled to a greater or lesser degree.
At present, many types of coupling between the teeth of excavators and the tooth-carriers are known, although all of them, given the contradictory conditions to be fulfilled and the hard work to which said components are subjected, exhibit defects with regard to what could be considered an ideal solution in terms of life of the tooth and avoidance of excessive wear on the tooth-carrier, enabling the latter to have an acceptably extended life.
U.S. Pat. No. 5,561,925 refers too a tooth assembly and retaining mechanism in which a nose portion matching with the socket of the tooth has parallel surfaces interconnected by a flat end surface.
U.S. Pat. No. 4,625,439 refers to an excavating tooth retaining means comprising a nose portion in which the tooth is fixed by means of a wedge in which the wear part lands directly against the holder.
However, none of said patents discloses the double inverted dovetail structure which characterizes the present invention.